With the rapid development of mobile communication, a base station antenna system with high electrical and mechanical performance may be required. High performance and small dimension are generally the trends of development of base station antenna systems, including, e.g., a relatively large electrical tilt, a high operating efficiency, a wide frequency band, and a compact structure. A phase shifter is used in a feeding network of the base station antenna system. For example, the phase shifter can improve antenna directivity of a base station, such that the base station transmits signals toward one or more designated directions with a relatively strong power strength.
The base station antenna system may include multiple phase shifters, and a number of the phase shifters may be increased based on an operation need. Traditionally, increasing a number of the phase shifters significantly increases a volume of the base station antenna system and, hence, increases layout difficulty of the feeding network.